Numerous efforts have been made to increase the safety, reliability and efficiency of motor vehicles and aircraft while reducing the overall cost of manufacturing. The need is driven by increased emphasis on motor vehicle safety and to improve driver awareness of possible dangers relative to vehicles in close proximity, particularly as the number of vehicles on the nation's highways is rapidly increasing thereby increasing the odds for vehicular accidents. Essential to meeting these efforts is incorporating new and expanding technologies into the manufacturing and development of vehicular lighting systems in their warning capability and reliability. Optical technology has offered many benefits by providing less expensive and more reliable light sources than were previously available. Specifically, efforts have been made to provide improved vehicular lighting systems which substantially reduce the number of lamps or high temperature operated halogen or halide lamps used in a vehicular lighting system.
U.S. Pat. No. 5,311,410 to Hsu et al. is an example of a vehicular lighting system in which a central light source distributes white light, through fiber optic cables, to various areas of a vehicle. The central light source includes high intensity discharge lamps. The fiber optic cables distribute light to various optical loads of the vehicle's lighting system, including headlamps, tail lights and dome lights. The flux of the light is controlled through mechanical switches that move segments of the fiber optic cables into and out of alignment.
Another example of a vehicular lighting system is disclosed in U.S. Pat. No. 4,930,049 to Davenport et al. in which a light bus network distributes high intensity white light from a central light source to various components of a vehicle. The light bus network includes a number of electro-mechanical controls such as shutters, as well as collimating and focusing lenses.
A further example of a vehicular lighting system involving a central light source with light carried by a series of optical fibers to an array of headlight lenses is disclosed in U.S. Pat. No. 4,868,718 to Davenport et al. The ends of the fibers are held in stationary alignment with their respective lenses, while optical wedge lens or rotating flat members are inserted between the fibers and their respective lenses to provide for shifting between high beam and low beam positions.
While the exiting art discloses vehicular lighting systems that have one or more light sources for servicing a plurality of optical fibers as light transmission media, such as disclosed in U.S. patents to Krammer U.S. Pat. No. 5,365,413; Currie U.S. Pat. No. 5,400,225; and Hsu et al. U.S. Pat. No. 5,436,805, these systems either remain complex in system design or still require high power noncoherent light sources that require special treatment due to their high temperature of operation or motor-rotated for providing selective distribution of light to desired fiber outputs adding to the cost and reliability of operation to the system. While U.S. Pat. No. 5,365,413 mentions a possibility of using laser diodes in vehicular lighting systems, there is no disclosure how this might be implemented, taking into consideration the use of high temperature halide lamps in a system housing of this patent adapted for their particular utility and thermal considerations not capable of accommodating a semiconductor laser output. On the other hand, there are vehicular lighting systems disclosing the use of light sources provided at a central location for easy access that have noncoherent lamp outputs coupled to fiber optic waveguides via color lenses that themselves function as the light output device for the system to provide selection between a non-red or a red light output on a single fiber for indication, respectively, of turn signal or brake light signal, as disclosed in the U.S. patent to Currie U.S. Pat. No. 5,400,225, mounted along the periphery of the rear window of the vehicle. Moreover, these prior vehicular lighting systems have the disadvantage of requiring numerous mechanical and thermal components to distribute light throughout a vehicle, thereby increasing both the size and expense of the systems.
What is needed is a centrally located vehicular lighting system that can accommodate coherent light sources that provides sufficient output brightness of light for fiber transmission to an optical load comprising the vehicular light output for a particular function such as a running light, turn signal light, backup light or a brake light.
It is an object of the present invention to provide an improved vehicular lighting system that is compact, lightweight, of simpler design and longer operational life.
It is a further object of the present invention to provide an improved vehicular lighting system that consumes substantially less power with dissipation of substantially less heat and provides for better space utilization with the availability of space in the vehicle compared to those currently suggested.
It is another object of this invention to provide light source redundancy to improve vehicular safety and reliability of the vehicular lighting system.
It is another object of this invention to provide multiple light sources per load for reliability and for providing moving vehicular conditional changes via illumination warning, such as vehicular braking or vehicular turning, in combination with multiple colors per optical load.
It is another object of this invention to provide a vehicular lighting system indicative to others via the same lighting of an applied brake pressure, hazard or other warning condition, or vehicular speed.
It is another object of this invention to provide a vehicle with an encoded light beam output for signaling data or information from a vehicle to roadside information gathering equipment such as a toll booth fee, parking meter fee, or vehicular identification for checking location and vehicular ID number.